# std::fmax, std::fmaxf, std::fmaxl

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< cpp‎ | numeric‎ | math

Defined in header `<cmath>` |  |
| (1) |
float fmax ( float x, float y ); double fmax ( double x, double y ); long double fmax ( long double x, long double y ); |  | (until C++23)
constexpr /*floating-point-type*/ fmax ( /*floating-point-type*/ x, /*floating-point-type*/ y ); |  | (since C++23)
float fmaxf( float x, float y ); | (2) | (since C++11) (constexpr since C++23)
long double fmaxl( long double x, long double y ); | (3) | (since C++11) (constexpr since C++23)
SIMD overload (since C++26) |  |
Defined in header `<simd>` |  |
template< class V0, class V1 > constexpr /*math-common-simd-t*/<V0, V1> fmax ( const V0& v_x, const V1& v_y ); | (S) | (since C++26)
Additional overloads (since C++11) |  |
Defined in header `<cmath>` |  |
template< class Integer > double fmax ( Integer x, Integer y ); | (A) | (constexpr since C++23)

1-3) Returns the larger of two floating point arguments, treating NaNs as missing data (between a NaN and a numeric value, the numeric value is chosen). The library provides overloads of `std::fmax` for all cv-unqualified floating-point types as the type of the parameters.(since C++23)

S) The SIMD overload performs an element-wise `std::fmax` on v_xand v_y. (See `math-common-simd-t` for its definition.) | (since C++26)

A) Additional overloads are provided for all integer types, which are treated as double. | (since C++11)

### Parameters

x, y | - | floating-point or integer values

### Return value

If successful, returns the larger of two floating point values. The value returned is exact and does not depend on any rounding modes.

### Error handling

This function is not subject to any of the error conditions specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

- If one of the two arguments is NaN, the value of the other argument is returned.
- Only if both arguments are NaN, NaN is returned.

### Notes

This function is not required to be sensitive to the sign of zero, although some implementations additionally enforce that if one argument is +0 and the other is -0, then +0 is returned.

The additional overloads are not required to be provided exactly as (A). They only need to be sufficient to ensure that for their first argument num1 and second argument num2:

If num1 or num2 has type long double, then std::fmax(num1, num2) has the same effect as std::fmax(static_cast<long double>(num1), static_cast<long double>(num2)). Otherwise, if num1 and/or num2 has type double or an integer type, then std::fmax(num1, num2) has the same effect as std::fmax(static_cast<double>(num1), static_cast<double>(num2)). Otherwise, if num1 or num2 has type float, then std::fmax(num1, num2) has the same effect as std::fmax(static_cast<float>(num1), static_cast<float>(num2)). | (until C++23)
If num1 and num2 have arithmetic types, then std::fmax(num1, num2) has the same effect as std::fmax(static_cast</*common-floating-point-type*/>(num1), static_cast</*common-floating-point-type*/>(num2)), where /*common-floating-point-type*/ is the floating-point type with the greatest floating-point conversion rank and greatest floating-point conversion subrank between the types of num1 and num2, arguments of integer type are considered to have the same floating-point conversion rank as double. If no such floating-point type with the greatest rank and subrank exists, then overload resolution does not result in a usable candidate from the overloads provided. | (since C++23)

### Example

Run this code

    #include <cmath>
    #include <iostream>

    int main()
    {
        std::cout << "fmax(2,1)    = " << std::fmax(2, 1) << '\n'
                  << "fmax(-Inf,0) = " << std::fmax(-INFINITY, 0) << '\n'
                  << "fmax(NaN,-1) = " << std::fmax(NAN, -1) << '\n';
    }

Output:

    fmax(2,1)    = 2
    fmax(-Inf,0) = 0
    fmax(NaN,-1) = -1

### See also

isgreater (C++11) | checks if the first floating-point argument is greater than the second (function)
fminfminffminl (C++11)(C++11)(C++11) | smaller of two floating point values (function)
max | returns the greater of the given values (function template)
max_element | returns the largest element in a range (function template)
minmax (C++11) | returns the smaller and larger of two elements (function template)
minmax_element (C++11) | returns the smallest and the largest elements in a range (function template)
C documentation for fmax

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